If you want to build these someplace out in the open, you can use dowels instead of rope- drill holes through the sides of the studs for them to run through. Or tack across some thin finish molding. The whole thing will also look much nicer with some molding put on like a picture frame around the entire shelf.
I also hung a thermometer with a humidity sensor; to see what kind of storage conditions the room really provided.
So, out of six feet of otherwise useless space, I can now store several dozen jars or cans.